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<H1>IBM Visualization Data Explorer Programmer&#39;s Reference</H1>
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<H3><A NAME="HDRDXGCEV" HREF="progu097.htm#PToC_253">DXGetCacheEntry,
DXGetCacheEntryV</A></H3>
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<P><STRONG>Function</STRONG>
<P>
Retrieve a cache entry.
<P><STRONG>Syntax</STRONG>
<BR>
<TT><STRONG><BR>
&#35;include &lt;dx/dx.h&gt;<BR>
<P><BR>
Object DXGetCacheEntry(char *function, int key, int n, ...)<BR>
Object DXGetCacheEntryV(char *function, int key, int n, Object *in)<BR>
</STRONG></TT><BR>
<P><STRONG>Functional Details</STRONG>
<P>
Both routines return the Object referenced by a cache entry.
The cache is indexed by a key created from <TT><STRONG>function</STRONG></TT>,
<TT><STRONG>key</STRONG></TT>, <TT><STRONG>n</STRONG></TT>, and the Objects in
the Array <TT><STRONG>in</STRONG></TT>.
These must be the same values as those used when the Object was placed
in the cache with <TT><STRONG>DXSetCacheEntry</STRONG></TT>.
<P><B>Notes: </B><OL>
<P><LI>Because Data Explorer modules follow pure function semantics, the cache
should <I>not</I> be used to store a state that affects the
output of the module.
A module must always be able to recreate the Object from the same set
of inputs; the cache should only be used as an optimization tool.
<P><LI>On a multiprocessor machine, processor local information should
<I>not</I> be stored in the cache, since its contents may be
retrieved on another processor.
<P><LI>The cache is local to one machine and cannot be used to communicate
information between modules on different machines when running in
distributed mode.
</OL>
Since DXGetCacheEntry returns an Object that is referenced so that it
will not be deleted, you must delete it when you are finished with
it.
Failure to do so will result in a memory leak.
<P>
For additional details on the deletion of cached Objects, see
<TT><STRONG>DXSetCacheEntry</STRONG></TT>.
<P><STRONG>Return Value</STRONG>
<P>
Returns the cached output Object or returns <TT><STRONG>NULL</STRONG></TT>
but does not set an error code if no such cache entry exists.
<P><STRONG>See Also</STRONG>
<P>
<TT><STRONG>
<A HREF="progu130.htm#HDRDXDEL">DXDelete</A>,
<A HREF="progu288.htm#HDRDXREF">DXReference</A>,
<A HREF="progu304.htm#HDRDXSCEV">DXSetCacheEntry, DXSetCacheEntryV</A>,
<A HREF="progu190.htm#HDRDXGSOT">DXGetObjectTag, DXSetObjectTag</A>
</STRONG></TT>
<P>
<A HREF="progu059.htm#HDRCACHE">13.5 , "Cache"</A>.
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